Can you post a picture?
When i had something similar sounding to that it was just some sunscreen and wiped off with a wet cloth.
Did you try some interior cleaner on it?
It's not discolored, it's just dirty with your skin residue. Lightly wiping it with conditioner won't clean it off. You'll need to use an all purpose cleaner and a good microfiber towel and put a little pressure (nt too much) on it.